Case C-300/23, Kuxtabank: Judgment of the Court (Ninth Chamber) of 12 December 2024 (request for a preliminary ruling from the Juzgado de Primera Instancia No 8 de Donostia – San Sebastián – Spain) – NB v Kutxabank SA (Reference for a preliminary ruling – Consumer protection – Directive 93/13/EEC – Unfair terms in consumer contracts – Mortgage loan agreement – Term providing for a variable interest rate – Reference index based on the annual percentage rates of charge (APRC) of mortgage loans granted by savings banks – Official index established by a published administrative act – Information contained in the preamble to that act – Check relating to the requirement of transparency – Assessment of the unfair nature of the term – Principle of effectiveness)